What cause low gas mileage? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72gmcshorty · 12-27-2003, 10:06 PM

I was just wondering what causes a motor to have low gas mileage? I know the carb plays a large role but if you have a new 350, a old tired 350, and a high performance 350 (all with the same carb on it) what would cause the difference in gas mileage between them?

Martin64 · 12-27-2003, 10:10 PM

Quote:

Originally posted by 72gmcshorty
I was just wondering what causes a motor to have low gas mileage? I know the carb plays a large role but if you have a new 350, a old tired 350, and a high performance 350 (all with the same carb on it) what would cause the difference in gas mileage between them?

...the right foot.....

.......actually the fresh 350 won't get real good until it's broke in, the old tired 350 won't get good because it's worn out and the performance 350 depends on what it has in it.

cableguy0 · 12-27-2003, 10:23 PM

well on a performance the cam will be bigger most likely as well as the ports in the heads and the valves therefore more space to put fuel. not to mention if you have a performance motor your NOT gonna keep your foot out of it hardly ever because its just so damn much fun

. and most likely you wouldnt be using the same carb on a peroformance motor as you would a stocker whether its new or worn out

krue · 12-27-2003, 10:25 PM

Gas mileage is just a measure of the efficiency of the engine. A carbureted engine is only going to be just so efficient. The hi po engine could possibly get better mileage in the same application. But as Martin64 said, the hi perf. engine is gonna get the lead foot treatment.

12-27-2003, 10:06 PM	#1
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	What cause low gas mileage? I was just wondering what causes a motor to have low gas mileage? I know the carb plays a large role but if you have a new 350, a old tired 350, and a high performance 350 (all with the same carb on it) what would cause the difference in gas mileage between them? __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

12-27-2003, 10:23 PM	#3
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	well on a performance the cam will be bigger most likely as well as the ports in the heads and the valves therefore more space to put fuel. not to mention if you have a performance motor your NOT gonna keep your foot out of it hardly ever because its just so damn much fun. and most likely you wouldnt be using the same carb on a peroformance motor as you would a stocker whether its new or worn out __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

12-27-2003, 10:25 PM	#4
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	Gas mileage is just a measure of the efficiency of the engine. A carbureted engine is only going to be just so efficient. The hi po engine could possibly get better mileage in the same application. But as Martin64 said, the hi perf. engine is gonna get the lead foot treatment. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

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